1. Technical Field
The present invention relates to potassium niobate deposited bodies and methods for manufacturing the same, piezoelectric thin film resonators, frequency filters, oscillators, electronic circuits, and electronic apparatuses.
2. Related Art
In the telecommunications field, accompanying the increase in the transmission rate, the transmission frequency is advancing toward higher frequencies. Piezoelectric thin film resonators (i.e., film bulk acoustic resonators: FBARs) are attracting attention as devices for achieving such higher frequencies. Because the development of piezoelectric thin film resonators is also directed toward achieving further miniaturization and higher efficiency, a larger electromechanical coupling coefficient is needed.
It has been found that a single crystal substrate of potassium niobate (KNbO3) (a=0.5695 nm, b=0.3973 nm and c=0.5721 nm as an orthorhombic system expression, and a=0.4015 nm as a cubic system expression) exhibited a large value of electromechanical coupling coefficient. For example, as described in Jpn. J. Appl. Phys. Vol. 37 (1998) 2929, it was confirmed by experiments that a 0° Y-cut X propagation KNbO3 single crystal substrate would exhibit a very large value of electromechanical coupling coefficient reaching as much as about 50%. However, it may be difficult to manufacture a piezoelectric thin film resonator by forming a thin film of potassium niobate on a certain substrate having a large area.